Practically, it saves me from having to use another set of speakers (you would not use 2 sets of speakers at the same time and I usually use headphones) and it also saves me from having to have or use 3 monitors which takes up more space and costs more.

My partner doesn't use her computer a lot. When she does, all the hardware is available for her. I use the 2nd monitor during development, gaming, watching movies, and RDP session.

As per some comments, I don't see how a VM would replace this use-case but I do understand its niche. Still, it saves us space.

I think both of my current ones have built in (crappy) sound and both HDMI and Display-Port inputs.

Also, that feature you mentioned, while it works with some RCs (generally "source" or "input" key), doesn't take into account all the inputs which I am not using. So I need to go through a list of 4 or 5 devices including DVB-C cause yeah my monitor has that support even though I've never used that input. That's annoying.

It gets annoying the more often you gotta switch. For employees of government (like the mentioned example of the Pentagon) that's gonna be more often than not. Any downtime is then a waste because even if its merely 20 seconds back and forth it quickly adds up.

It could even make sense to have KVMs in businesses where they want to keep certain data strictly internal. But as long as companies aren't being punished for data leaks that doesn't have priority. Perhaps we'll eventually see a rise again of KVMs.

> "a person with whom one shares an intimate relationship : one member of a couple"

https://www.merriam-webster.com/dictionary/partner

One can use "spouse" or "significant other" to avoid the perception of being passive-aggressive.

If you took an ancient (but still available to buy) 25-pin 'parallel port' 4-port switch box with a rotary dial:

https://photography-909a.kxcdn.com/product-images/03292/600/...

And wired up the HDMI of two machines to output ports 1 & 3[1]. Then wired up the HDMI to the display to the input port (so effectively using the switch 'backwards'). As you are just simulating unplugging and re-plugging in the HDMI cable from each machine, via the switch, then surely this would work?

There would be a bit of delay after switching as the HDMI/HDCP handshake completes, but unless you are switching every few minutes it should be usable?

If it does work, then you've got 6 pins in the switch left to play with which could be used to switch usb devices (via a downstream hub)

I've not done this, but have thought about it for a while now.

----

[1] Not ports 1 & 2 as you want to ensure total electrical isolation between the devices during switching.

The problem you will have is that the signals require high bandwidth and the cables are carefully designed to have low crosstalk, high immunity to noise (both via twisted pairs) and a 100 ohm characteristic (dynamic) impedance (how the cables are constructed, insulation thicknesses, how they are twisted).

DB-25 switches work for simple single ended low frequency signals. The physical switch will wreck havoc with the interpair skew, far-end crosstalk, attenuation and differential impedance.

HDMI 1.3 defines two cable categories: Category 1-certified cables, which have been tested at 74.5 MHz (which would include resolutions such as 720p60 and 1080i60), and Category 2-certified cables, which have been tested at 340 MHz (which would include resolutions such as 1080p60 and 2160p30). Category 1 HDMI cables are marketed as "Standard" and Category 2 HDMI cables as "High Speed". This labeling guideline for HDMI cables went into effect on October 17, 2008. Category 1 and 2 cables can either meet the required parameter specifications for interpair skew, far-end crosstalk, attenuation and differential impedance, or they can meet the required nonequalized/equalized eye diagram requirements. [1]

[1] https://en.wikipedia.org/wiki/HDMI#Cables

Also, there are sequencing requirements. Look carefully at a USB-A plug, and you'll see that the power and ground traces are longer than the data traces: when plugging the USB cable, the power is connected first, before the data; when unplugging, the order is reversed. HDMI probably has similar requirements, perhaps with more steps. Again, I doubt that ancient box can do that.

The output device "ensures" the display device is authorized via a key to output.

So, you would need an intermediary device that would accept any incoming signal, while also having a legit handshake with the output device.

So, as you switch "inputs", there is no additional authorization required, because the output device does not detect any changes.

My guess is that with KVMs disappearing from server racks, there isn't enough volume to get the prices we used to get.

https://usa.yamaha.com/products/audio_visual/av_receivers_am...

Something that can reliably connect to random/miscellaneous projects would be really useful to me!

It seems to work fine although I haven't used it a huge amount.

Single Monitor https://store.level1techs.com/products/kvm-switch-single-mon...

Dual Monitor https://store.level1techs.com/products/kvm-switch-dual-monit...

And once you plug in a dedicated 5V power supply they are rock solid.

http://www.cablechick.com.au/cables/4-port-hdmi-switcher.htm...

(I have also tried a simple powered switch with an IR remote control, but it caused signal degradation & glitches.)

Seriously though, I am a regular user of DVI and VGA KVMs, which have served me well over the years, but now as I migrate to HDMI or DisplayPort connectors and higher resolutions, I'm finding myself having to re-think how I hook everything together.

I tried plugging the cable into my KVM switch and it worked okay on the Windows 10 side but there was some hot-plugging kernel panic when switching to Linux (must file a bug report!)

So perhaps the future of KVM switches doesn't need video connectors such as VGA/DVI/DP if USB-C -> HDMI (as smartphones are adopting) becomes universal.

https://www.amazon.com/gp/product/B071CJWSPF/

https://www.amazon.com/Plugable-One-Button-Swapping-Between-...

4k 60fps 4/4/4 color no problem

And no, no one needs 4k where a KVM belongs (which is in a server room).

Everything I tried was garbage:

http://penguindreams.org/blog/4k-uhd-kvm-switches-the-starte...

There are a few in the $500+ range I have not tried, but you are wrong, there are use cases for 4k switching. I mean, do you really want to have two 4k monitors next to each other when you could just have one for half the cost?

Your setup is rather peculiar, and wastes a computer. It is usually done with dual-booting or virtualization, while multiple inputs (which I bet your screen has) or HDMI switch could handle it as well (although without handling keyboard/mouse).

KVM's were designed for server environments, sold to server environments, and only take server environments into consideration where VGA+USB will remain the status quo for years to come.

If you're really set on a KVM, take a 4k-capable standalone HDMI switch, a USB "switch" (https://www.amazon.com/IOGEAR-Computer-Peripheral-Sharing-GU..., or a USB KVM), and an arduino to strap it together as a unit. Unless servers do away with VGA (hahah, no), I doubt you'll find a product for an affordable price that does what you want.

I have often wondered why no one offers wireless keyboard/mouse combos with multiple USB fobs and a switch on the keyboard to change which fob it talks to.

(Confidence? "Wait, wait, am I talking to data2 or web4 or what?)

KVM was a just-barely-competent solution to a hair-on-fire (=== must-solve-now) problem.